The report is the strongest sign yet that Iran seeks to build a nuclear arsenal, despite claims to the contrary.

A 2007 National Intelligence Estimate given to then-President George W. Bush indicated that Iran had abandoned its weapons-related research in 2003. However, an ongoing investigation by the Fox News Specials Unit concludes that more that 600 entities were working inside Iran to support its program, and at least 40 sites where the work is taking place are suspected to still exist across the country.

The Qom uranium enrichment construction site, hidden deep in the mountains of Iran, causes concern among many investigators. Intelligence shows that security walls have recently doubled around the site.

Iran insists its nuclear program is for peaceful purposes, not weapons production.

While some of the suspected secret nuclear work outlined in the annex could also be used for peaceful purposes, "others are specific to nuclear weapons," said the confidential report obtained by The Associated Press.

Some of the information contained in the annex was new -- including evidence of a large metal chamber at a military site for nuclear-related explosives testing. The bulk, however, was a compilation and expansion of alleged work already partially revealed by the agency.

But a senior diplomat familiar with the report said its significance lay in its comprehensiveness, thereby reflecting that Iran apparently had engaged in all aspects of testing that were needed to develop such a weapon. Also significant was the agency's decision to share most of what it knows or suspect about Iran's secret work the 35-nation IAEA board and the U.N. Security Council after being stonewalled by Tehran in its attempts to probe such allegations.

Copies of the report went to board members and the council, which has imposed four sets of U.N. sanction on Tehran for refusing to stop activities that could be used to make a nuclear weapon and refusing to cooperate with IAEA attempts to fully understand its nuclear program.

The agency said the annex was based on more than 1,000 pages of intelligence and other information forwarded by more than 10 nations and material gathered by the IAEA itself.

He told Israel Radio that he did not expect any new U.N. sanctions on Tehran to persuade it to stop its nuclear defiance, adding: We continue to recommend to our friends in the world and to ourselves, not to take any option off the table."

The "all options on the table" phrase is often used by Israeli politicians to mean a military assault, and Israeli government members have engaged in increased saber rattling recently suggesting that an attack was likely a more effective way to stop Iran's nuclear program than continued diplomacy.

Russian President Dimitry Medvedev warned against threatening Iran with the use of force. Speaking in Berlin Tuesday, Medvedev said threats could lead to a war, "and for the Middle East this would be a catastrophe."

China's Foreign Ministry Spokesman Hong Lei said Tuesday that while Beijing is firmly opposed to any use of force, "the Iranian side should also show flexibility and sincerity."